1. Genetics: RNA and Protein Synthesis

2. Review
Protein synthesis or creation is important for cellular function.
Proteins are made of amino acids and our DNA provides the instructions for assembling amino acids in the proper order
The nucleus holds the key for protein synthesis.

3. Ribonucleic Acid (RNA)
Like DNA, RNA is a long molecule made up of smaller units called nucleotides
Pictured: DNA molecule showing nucleotide monomers

4. Ribonucleic Acid (RNA)
There are three main differences between RNA and DNA:
The 5-carbon sugar in RNA is ribose
RNA is generally single-stranded
RNA contains uracil in place of thymine
Pictured: uracil nitrogenous base, single-strand RNA, ribose sugar

5. Ribonucleic Acid (RNA)
Pictured: comparison of DNA and RNA molecules

6. mRNA
In the cell’s nucleus, DNA is used as a template and copied to create messenger RNA (mRNA) during a process called transcription
mRNA is made of ribose instead of deoxyribose, is a single strand, and the nucleotide base Thymine is replaced with Uracil.

7. Types of RNA
Messenger RNA (mRNA)- RNA molecules that carry copies of instructions for assembling amino acids into proteins
Pictured: mRNA strand (in red) being made from a DNA template strand

8. rRNA
Ribosomal RNA or rRNA is made up of a group of proteins which form ribosomes.
During translation, the ribosome reads three mRNA nucleotides at a time with each nucleotide triplet (codon) calling for a specific amino acid.

9. Types of RNA
Ribosomal RNA (rRNA)- RNA on ribosomes where amino acids are assembled into proteins
Pictured: ribosome with small and large subunits

10. tRNA
That’s where Transfer RNA or tRNA comes in. As the ribosome reads the nucleotide triplet (codon) of mRNA, a specific tRNA molecule matches up with the sequence and carries with it a specific amino acid.
The amino acid then binds to the growing amino acid (polypeptide) chain until the mRNA message comes to a stop and a protein is created.

11. Amino Acids, Polypeptides, and Proteins
A polypeptide is a chain of amino acids One or more polypeptides make up a protein

12. Types of RNA
Transfer RNA (tRNA)- RNA molecules that transfer each amino acid to the ribosome for protein assembly
Pictured: a two-dimensional and three-dimensional diagram of tRNA structure

13. From DNA to Protein
Proteins are synthesized (made) through a two-step process: Transcription  DNA is transcribed into mRNA
DNA
mRNA

14. From DNA to Protein Translation  mRNA is decoded to make proteins
amino acids

15. Protein Synthesis Summary
DNA  RNA  Protein
Transcription Translation
(nucleus) (cytoplasm)
Transcription takes place in the nucleus. Translation takes place in the cytoplasm at ribosomes.

16. Protein Synthesis Summary1 2 3
DNA  RNA  Protein 1 2
Diagram labeling DNA, RNA, and Protein. DNA is transcribed into mRNA in the nucleus. mRNA is decoded and amino acids are assembled in the cytoplasm at the ribosomes. 3

17. Transcription DNA  RNA DNA is transcribed into mRNA
Transcription occurs in the nucleus
Pictured: mRNA strand being made from a DNA template strand in the nucleus.

18. Transcription DNA  RNA
Process is similar to DNA replication Uracil replaces thymine: adenine-uracil base pairing
Pictured: mRNA strand being made from a DNA template strand.

19. Transcription
Transcribe the following DNA sequence into mRNA:
T A G

20. Remember: uracil replaces thymine in mRNA
Transcription
Transcribe the following DNA sequence into mRNA:
T A G
A U C
Remember: uracil replaces thymine in mRNA

21. Transcription DNA strands are separated by RNA polymerase
RNA polymerase uses one strand of DNA as a template to assemble nucleotides into a strand of mRNA

22. Transcription

23. Transcription RNA edits the molecule
The mRNA strand is released into the cytoplasm
Pictured: mRNA being released into the cytoplasm

24. Translation RNA  Protein
mRNA is decoded to produce proteins Translation occurs in the cytoplasm
After transcription, mRNA leaves the nucleus and goes to a ribosome in the cytoplasm for translation (to be decoded).

25. Translation
mRNA strand attaches to a ribosome in the cytoplasm

26. Translation
mRNA is read three base letters at a time- called a codon

27. Translation
tRNA brings a complementary amino acid and pairs its anticodon with the mRNA codon

28. Translation
The ribosome forms a peptide bond between amino acids and releases the tRNA molecule 1 2 1 2

29. Translation
The polypeptide chain continues to grow until the ribosome reaches a “stop” codon in which the chain and mRNA are released

30. The Genetic Code
The “language” that cells use to make proteins from a DNA sequence

31. The Genetic Code DNA is transcribed into mRNA
mRNA is read 3 base letters at a time
One mRNA codon codes for one specific amino acid
There are 20 different amino acids
Use an mRNA codon table to find the amino acid coded for by the codon

32. The Genetic Code
Pictured: mRNA codon charts

33. The Genetic Code Find the amino acid coded for by the codon GCA
Pictured: mRNA codon charts

34. C (second base) G (first base) A (third base) Codon: GCA
Pictured: mRNA codon charts G
(first
base) A
(third
base)
Find the bases on the 1st, 2nd, and 3rd columns

35. C (second base) G (first base) A (third base) Codon: GCA
Pictured: mRNA codon charts
Find where the three points meet

36. C (second base) G (first base) A (third base) Codon: GCA
Pictured: mRNA codon charts
GCA codes for the amino acid Alanine

37. Transcribe and translate mRNA from a DNA sequence to an amino acid
From DNA to Protein
Transcribe and translate mRNA from a DNA sequence to an amino acid
From DNA to Protein
DNA
TAC
AAG
TTT
mRNA
tRNA
Amino Acid

38. mRNA Codon Table
Pictured: mRNA codon chart

39. Transcribe and translate mRNA from a DNA sequence to an amino acid
From DNA to Protein
Transcribe and translate mRNA from a DNA sequence to an amino acid
From DNA to Protein
DNA
TAC
AAG
TTT
mRNA
AUG
UUC
AAA
tRNA
UAC
UUU
Amino Acid
Methionine
(start)
Phenylalanine
Lysine